This disclosure refers to a thermal fuse for an electrical circuit generally of the type known from DE 10 2014 111 772 B4, for example.
In the fuse disclosed in DE 10 2014 111 772 B4, two conductors are electrically connected to each other by means of a mechanically preloaded contact arm. The contact arm is welded to one of the two electrical conductors, and soldered to the other. When the fuse activation temperature is reached, the soldered joint loses its strength, such that the preloaded contact arm lifts from the conductor in question and the circuit is thus interrupted. Instead of a welded joint, the contact arm may also be connected to one of the two conductors by means of another soldered joint, which only loses its strength at a higher temperature, such that when the activation temperature of the fuse is reached the same end of the contact arm always lifts from one of the two conductors.
This known fuse is well suited for circuits with low electrical voltages of up to 12 volts, such as those used in passenger vehicles. However, the opening gap that can be achieved is relatively small, and is insufficient for applications with higher voltages, e.g., 48 volts. At higher voltages there is therefore a risk that an electrical arc will form between a conductor and the lifted contact arm as the fuse is opened. This arc is a hazard that can lead to a fire.